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    <script>
         Array.prototype.mySome = function (fn) {

        for (let i = 0; i < this.length; i++) {
          if (fn(this[i], i, this)) {
           return true
            }  
        }

      return false
    } 
    //  空数组调用some返回false
     const arr = [1,2,3]

     const flag = arr.mySome(item => {
     console.log(1);
    //  写return返回turn，不写返回false
        return  item === 2
    })

    console.log(flag);
    </script>
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